The only Harbor Freight model I have, is The Centech pinpointer, wouldn't think it a good idea to mess with the coil. You can take pretty much anything apart, that's usually the easy part. It's the putting it back together, and having it work, afterward, that's the tricky part.
Really not enough information to even guess. Both of of my machines come apart, and can use different size coils. Have heard of machines with hardwired coils.
